As 3D (three-dimensional) film becomes popular and gross in recent years, consumer demands for 3D (three-dimensional) digital images have also increased. As for the current major 3D digital images, an actual shooting of stereo image using a stereo camera has gradually become one of the major trends as in addition to the use of computer synthesis and 2D to 3D conversion. In general, the actual shooting using the stereo camera is to use more than two stereo cameras to perform image capture shooting of the stereo image. Following the increases in the consumer demands for the 3D digital images, a variety of stereo cameras and filming equipments have sprung and become available. Currently, the most common stereo cameras are mainly divided into two major rigs: a side-by-side rig and a mirror rig.
In detail, a dimensional sense of the generated stereo image is based on a certain parallax between two eyes since the two eyes of the human are mainly aligned along a horizontal direction; in other words, an effective stereo image parallax is a parallax in the horizontal direction, and therefore, no obvious parallax in a vertical direction or other directions should be appeared in an artificial stereo image, so as to avoid the human eyes from being unable to focus favorably when viewing the artificial stereo image due to a parallax other than the parallax in the horizontal direction, thereby effecting a stereo image quality or even producing a dizziness or discomfort feeling. Currently, before shooing the stereo image, the stereo camera has to go through a manually calibration process so as to enable a plurality of camera shots in the stereo camera to be firstly and favorably aligned, and then a distance between and a direction of each camera shot are correspondingly adjusted according to shooting requirements. However, since a current major method is to adopt the manual calibration method, in general, an experienced calibration technician has to spend about 2 to 3 hours just to perform one calibration, whereas there are usually more than 200 camera shots when shooting a 3D film; in other words, time and money spent on a film is very impressive, and thus, a longer calibration time, other than causing a great loss in money, may most likely result in shooting pressures on casts and crew (e.g., schedule factors of movie stars or an allowance of shooting time limit in a special country allows). Therefore, how to provide a fast and accurate calibration method for the stereo camera has become one of the most current problems to be solved.